My C++ project always shows a dialog 'This project is out of date' every time I run from Visual Studio?

This can be caused if the path to SmartPtr.h is not specified, even though the Additional Include path is set to the Liquid Runtime Include folder.

This is an issue with Visual Studio as it is able to find the include file, but marks the project as requiring a build.

The solution is to change the full path to SmartPtr.h to be correct.